1. Field of the Invention
The present invention relates generally to a mounting fixture for an optical instrument such as an optical correlator, with the mounting fixture providing for the precise mounting and positional adjustment therein of an element at least along two transverse x and y axes, and also rotationally along .theta. in roll about the z axis, .gamma. in pitch about the x axis, and .beta. in yaw about the y axis.
More particularly, the subject invention pertains to a mounting fixture as described providing for the precise mounting and decoupled positional adjustment of an element, such as a glass plate upon which a multiple holographic lens is recorded, or a multiple matched filter, in an optical correlator. The mounting fixture of the present invention enables precise x and y, and roll, pitch and yaw (.theta.,.gamma.,.beta.) positional adjustments and alignments to be made for an element, and then fixedly mounts the element stably in position in the optical correlator.
2. Discussion of the Prior Art
A matched filter optical correlation system is disclosed in U.S. patent application Ser. No. 814,209, filed Dec. 27, 1985, relative to which the mounting fixture of the present invention was designed and developed. The optical correlation system disclosed therein optically compares an input image with optical information stored in multiple matched filters to provide identification, position, and aspect information about the input image. In one disclosed embodiment, the input image is directed onto a spatial light modulator to spatially modulate a coherent beam of radiation. The spatially modulated radiation beam is directed onto a glass plate having recorded thereon a multiple holographic lens which performs a multiple number of Fourier transformations thereon to obtain an array of a multiple set of Fourier transforms of the spatially modulated radiation beam. A corresponding array of matched filters has the array of Fourier transforms incident thereon, with each matched filter comprising a Fourier transform hologram of a scale or an aspect view of an object of interest. Each matched filter passes an optical signal in dependence upon the degree of correlation of the Fourier transform of the spatially modulated radiation beam with the Fourier transform hologram recorded thereon. An inverse Fourier transform lens receives the optical outputs of the array of matched filters, and performs an inverse Fourier transformation on the optical outputs. A detector detects the inverse Fourier transform of the optical outputs, and produces an electrical output signal representative thereof. This signal is called the correlation signal, and the plane of the signal, the correlation plane.
One problem with this type of optical correlator is that of obtaining a proper and precise positional alignment and mounting of the glass plate having recorded thereon the multiple holographic lens. A typical matched filter optical correlator as described hereinabove is normally initially set or adjusted such that the multiple holographic lens is properly positioned along x and y coordinates and also properly angularly positioned with respect to roll, pitch and yaw (.theta.,.gamma.,.beta.) angular adjustments. The present state of the art of optical correlators has improved to the point that the multiple holographic lens can be designed to be fixed in place and not require a z adjustment along the optical axis. Moreover, it should be pointed out that in the present state of the art, the mounting fixture of the present invention is designed for relatively fine translational and angular adjustments and alignments, not for gross positional alignments. The mounting fixture of the present invention could also be utilized to mount a matched filter or multiple matched filter in the optical correlator, in which case the axial distance along the z axis (optical axis), the .gamma., pitch adjustment, and the .beta. yaw adjustment are normally initially properly set. Moreover, these adjustments generally remain properly set and aligned in particular embodiments of the optical correlator, and do not require re-adjustment each time a new matched filter is placed therein.